Image processing device, drive control device, light source control device, image forming apparatus, and image processing method

ABSTRACT

An image processing device includes circuitry to: acquire an image matrix including a target pixel from first image data having a first resolution; determine whether one or more detection patterns match the image matrix; and perform edge enhancement on the target pixel and convert the first resolution into a second resolution to convert the target pixel into second image data, if the image matrix matches any of the one or more detection patterns. The first image data includes a plurality of pixels each including first and second pixel values respectively indicating image information and whether each of the plurality of pixels is an area where a specific object is drawn. The one or more detection patterns, each including a plurality of pixels each including the first and second pixel values, are patterns to detect a pixel forming an edge portion where the first and second pixel values vary between pixels.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is based on and claims priority pursuant to 35U.S.C. § 119(a) to Japanese Patent Application No. 2016-189582, filed onSep. 28, 2016, in the Japan Patent Office, the entire disclosure ofwhich is hereby incorporated by reference herein.

BACKGROUND Technical Field

Embodiments of the present disclosure generally relate to an imageprocessing device, a drive control device, a light source controldevice, an image forming apparatus, and an image processing method.

Related Art

Various types of electrophotographic image forming apparatuses areknown, including copiers, printers, facsimile machines, andmultifunction machines having two or more of copying, printing,scanning, facsimile, plotter, and other capabilities. Such image formingapparatuses usually form an image on a recording medium according toimage data. Specifically, in such image forming apparatuses, forexample, a charger uniformly charges a surface of a photoconductor as animage bearer. An optical writer irradiates the surface of thephotoconductor thus charged with a light beam to form an electrostaticlatent image on the surface of the photoconductor according to the imagedata. A developing device supplies toner to the electrostatic latentimage thus formed to render the electrostatic latent image visible as atoner image. The toner image is then transferred onto a recording mediumeither directly, or indirectly via an intermediate transfer belt.Finally, a fixing device applies heat and pressure to the recordingmedium bearing the toner image to fix the toner image onto the recordingmedium. Thus, an image is formed on the recording medium.

Such image forming apparatuses employ image processing technology tothin text, lines, or the like, as edge enhancement, to prevent the text,lines, or the like, from being thickened.

SUMMARY

In one embodiment of the present disclosure, a novel image processingdevice includes circuitry to acquire an image matrix corresponding to anarea including a target pixel and pixels surrounding the target pixelfrom first image data having a first resolution. The first image dataincludes a plurality of pixels, each of which includes a first pixelvalue indicating image information and a second pixel value indicatingwhether each of the plurality of pixels is an area in which a specificobject is drawn. The circuitry determines whether one or more detectionpatterns match the image matrix thus acquired. Each of the one or moredetection patterns includes a plurality of pixels. Each of the pluralityof pixels includes the first pixel value and the second pixel value.Each of the one or more detection patterns is a pattern to detect apixel forming an edge portion in which each of the first pixel value andthe second pixel value varies between pixels. The circuitry performsedge enhancement on the target pixel and performs resolution conversionto convert the first resolution into a second resolution higher than thefirst resolution, to convert the target pixel into second image data, ifthe image matrix matches any of the one or more detection patterns.

Also described are a novel drive control device incorporating the imageprocessing device, a novel light source control device incorporating thedrive control device, a novel image forming device incorporating thelight source control device, and a novel image processing method.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be more readily obtained as the same becomesbetter understood by reference to the following detailed description ofembodiments when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is a schematic view of an image forming apparatus according to anembodiment of the present disclosure;

FIG. 2 is a diagram illustrating relative positions of optical sensorsincorporated in the image forming apparatus of FIG. 1;

FIG. 3 is a schematic view of an optical sensor and a transfer beltincorporated in the image forming apparatus of FIG. 1, particularlyillustrating a configuration of the optical sensor;

FIG. 4 is a top view of an optical scanner incorporated in the imageforming apparatus of FIG. 1;

FIG. 5 is a partial side view of the optical scanner, illustratingoptical paths from light sources to a polygon mirror;

FIG. 6 is a partial side view of the optical scanner, illustratingoptical paths from other light sources to the polygon mirror;

FIG. 7 is a partial side view of the optical scanner, illustratingoptical paths from the polygon mirror to photoconductor drums;

FIG. 8 is a block diagram of an electrical system of the opticalscanner;

FIG. 9 is a block diagram of an interface unit incorporated in theoptical scanner of FIG. 8;

FIG. 10 is a block diagram of an image processing unit incorporated inthe optical scanner of FIG. 8;

FIG. 11 is a diagram of a specific object drawn by dots;

FIG. 12A is a first example of a pixel;

FIG. 12B is a second example of the pixel;

FIG. 12C is a third example of the pixel;

FIG. 12D is a fourth example of the pixel;

FIG. 13 is a block diagram of a drive control unit incorporated in theoptical scanner of FIG. 8;

FIG. 14 is a block diagram of a modulation signal generator incorporatedin the drive control unit of FIG. 13;

FIG. 15 is a diagram of the resolution conversion executed by aresolution converter incorporated in the modulation signal generator ofFIG. 14, illustrating relative positions of bits representing imageinformation and tag information in a first resolution before theresolution is converted, and relative positions of bits representing theimage information and the tag information in a second resolution afterthe resolution is converted;

FIG. 16 is a block diagram of the resolution converter;

FIG. 17 is a diagram of a first example of an image matrix;

FIG. 18A is a diagram of a first example of a first type of detectionpattern;

FIG. 18B is a second example of the first type of detection pattern;

FIG. 18C is a diagram of a third example of the first type of detectionpattern;

FIG. 19A is a diagram of a detection pattern corresponding to anupper-left detection pattern of FIG. 18A;

FIG. 19B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 19A;

FIG. 20A is a diagram of a detection pattern corresponding to anupper-right detection pattern of FIG. 18A;

FIG. 20B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 20A;

FIG. 21A is a diagram of a detection pattern corresponding to alower-left detection pattern of FIG. 18A;

FIG. 21B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 21A;

FIG. 22A is a diagram of a detection pattern corresponding to alower-right detection pattern of FIG. 18A;

FIG. 22B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 22A;

FIG. 23A is a diagram of a detection pattern corresponding to anupper-left detection pattern of FIG. 18B;

FIG. 23B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 23A;

FIG. 24A is a diagram of a detection pattern corresponding to anupper-right detection pattern of FIG. 18B;

FIG. 24B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 24A;

FIG. 25A is a diagram of a detection pattern corresponding to alower-left detection pattern of FIG. 18B;

FIG. 25B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 25A;

FIG. 26A is a diagram of a detection pattern corresponding to alower-right detection pattern of FIG. 18B;

FIG. 26B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 26A;

FIG. 27A is a diagram of a detection pattern corresponding to anupper-left detection pattern of FIG. 18C;

FIG. 27B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 27A;

FIG. 28A is a diagram of a detection pattern corresponding to anupper-right detection pattern of FIG. 18C;

FIG. 28B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 28A;

FIG. 29A is a diagram of a detection pattern corresponding to alower-left detection pattern of FIG. 18C;

FIG. 29B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 29A;

FIG. 30A is a diagram of a detection pattern corresponding to alower-right detection pattern of FIG. 18C;

FIG. 30B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 30A;

FIG. 31A is a diagram of line thinning and the resolution conversionperformed on a simple, quadrangular solid image;

FIG. 31B is a diagram of the line thinning and the resolution conversionperformed on a specific object drawn by dots;

FIG. 31C is a diagram of an image after the line thinning is performedwithout using a detection pattern;

FIG. 32A is a diagram of a first example of a second type of detectionpattern;

FIG. 32B is a second example of the second type of detection pattern;

FIG. 32C is a diagram of a third example of the second type of detectionpattern;

FIG. 33A is a diagram of a detection pattern corresponding to anupper-left detection pattern of FIG. 32A;

FIG. 33B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 33A;

FIG. 34A is a diagram of a detection pattern corresponding to anupper-right detection pattern of FIG. 32A;

FIG. 34B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 34A;

FIG. 35A is a diagram of a detection pattern corresponding to alower-left detection pattern of FIG. 32A;

FIG. 35B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 35A;

FIG. 36A is a diagram of a detection pattern corresponding to alower-right detection pattern of FIG. 32A;

FIG. 36B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 36A;

FIG. 37A is a diagram of a detection pattern corresponding to anupper-left detection pattern of FIG. 32B;

FIG. 37B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 37A;

FIG. 38A is a diagram of a detection pattern corresponding to anupper-right detection pattern of FIG. 32B;

FIG. 38B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 38A;

FIG. 39A is a diagram of a detection pattern corresponding to alower-left detection pattern of FIG. 32B;

FIG. 39B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 39A;

FIG. 40A is a diagram of a detection pattern corresponding to alower-right detection pattern of FIG. 32B;

FIG. 40B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 40A;

FIG. 41A is a diagram of a detection pattern corresponding to anupper-left detection pattern of FIG. 32C;

FIG. 41B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 41A;

FIG. 42A is a diagram of a detection pattern corresponding to anupper-right detection pattern of FIG. 32C;

FIG. 42B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 42A;

FIG. 43A is a diagram of a detection pattern corresponding to alower-left detection pattern of FIG. 32C;

FIG. 43B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 43A;

FIG. 44A is a diagram of a detection pattern corresponding to alower-right detection pattern of FIG. 32C;

FIG. 44B is a target pixel converted as a result of image processingassociated with the detection pattern of FIG. 44A;

FIG. 45 is a diagram of image processing by which an outlined quadrangleis drawn as a specific object on a dithering-pattern background;

FIG. 46 is a flowchart of an example of processing performed by theresolution converter.

FIG. 47A is a diagram of a variation of the line thinning performed on afirst set of blocks of pixels in a lateral direction;

FIG. 47B is a diagram of the variation of the line thinning performed ona second set of blocks of pixels in the lateral direction;

FIG. 47C is a diagram of the variation of the line thinning performed ona third set of blocks of pixels in a vertical direction;

FIG. 47D is a diagram of the variation of the line thinning performed ona fourth set of blocks of pixels in the vertical direction;

FIG. 48A is a diagram of a detection pattern to detect a far-edge pixelwhen black pixels construct text, a line, or a graphical shape and whitepixels construct a background;

FIG. 48B is a diagram of a detection pattern to detect an adjacent edgepixel when black pixels construct text, a line, or a graphical shape andwhite pixels construct a background;

FIG. 49A is a diagram of a detection pattern to detect a far-edge pixelwhen white pixels construct text, a line, or a graphical shape and blackpixels construct a background;

FIG. 49B is a diagram of a detection pattern to detect an adjacent edgepixel when white pixels construct text, a line, or a graphical shape andblack pixels construct a background;

FIG. 50 is a diagram of an example of image processing including theline thinning performed on input image data including pixels forming anedge portion between a black text line and a background;

FIG. 51 is a diagram of an example of image processing including theline thinning performed on input image data including pixels forming anedge portion between a white text line and a background;

FIG. 52 is a block diagram of a resolution converter according to asecond embodiment;

FIG. 53A is a diagram of image processing associated with a seconddetection pattern performed on image data that includes pixels forming astep and the edge portion;

FIG. 53B is a diagram of the image processing performed on the pixelsincluded in the image data of FIG. 53A;

FIG. 54 is a diagram of a second example of the image matrix;

FIG. 55A is a diagram of a first example of the second detectionpattern;

FIG. 55B is a second example of the second detection pattern; and

FIG. 55C is a diagram of a third example of the second detectionpattern.

The accompanying drawings are intended to depict embodiments of thepresent disclosure and should not be interpreted to limit the scopethereof. Also, identical or similar reference numerals designateidentical or similar components throughout the several views.

DETAILED DESCRIPTION

In describing embodiments illustrated in the drawings, specificterminology is employed for the sake of clarity. However, the disclosureof this patent specification is not intended to be limited to thespecific terminology so selected and it is to be understood that eachspecific element includes all technical equivalents that have the samefunction, operate in a similar manner, and achieve similar results.

Although the embodiments are described with technical limitations withreference to the attached drawings, such description is not intended tolimit the scope of the disclosure and not all of the components orelements described in the embodiments of the present disclosure areindispensable to the present disclosure.

In a later-described comparative example, embodiment, and exemplaryvariation, for the sake of simplicity like reference numerals are givento identical or corresponding constituent elements such as parts andmaterials having the same functions, and redundant descriptions thereofare omitted unless otherwise required.

As used herein, the singular forms “a”, “an”, and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

It is to be noted that, in the following description, suffixes K, C, M,and Y denote colors black, cyan, magenta, and yellow, respectively. Tosimplify the description, these suffixes are omitted unless necessary.

Referring now to the drawings, a description is given of an imageprocessing device, a drive control device, a light source controldevice, an image forming apparatus, and an image forming methodaccording to embodiments of the present disclosure.

Initially, a description is given of an image forming apparatusaccording to an embodiment of the present disclosure. The image formingapparatus may be a copier, a facsimile machine, a printer, amultifunction peripheral (MFP) having at least two of copying, printing,scanning, facsimile, and plotter functions, or the like. According to anembodiment of the present disclosure, the image forming apparatus is acolor printer (hereinafter referred to as an image forming apparatus2000) that forms color and monochrome toner images on a recording mediumby electrophotography. Alternatively, the image forming apparatus may bea monochrome printer that forms a monochrome toner image on a recordingmedium.

Now, a description is given of a first embodiment.

FIG. 1 is a schematic view of the image forming apparatus 2000.

The image forming apparatus 2000 transfers toner to a sheet as arecording medium to produce a printed matter. Specifically, the imageforming apparatus 2000 is a multicolor printer employing a tandemstructure in which image forming devices for forming toner images indifferent colors are aligned. More specifically, the image formingdevices respectively form black, cyan, magenta, and yellow toner images,which are superimposed one atop another and formed as a composite,full-color toner image.

As illustrated in FIG. 1, the image forming apparatus 2000 includes anoptical scanner 2010 as a light source control device, fourphotoconductor drums 2030 a, 2030 b, 2030 c, and 2030 d (hereinaftercollectively referred to as photoconductor drums 2030), four cleaners2031 a, 2031 b, 2031 c, and 2031 d (hereinafter collectively referred toas cleaners 2031), four chargers 2032 a, 2032 b, 2032 c, and 2032 d(hereinafter collectively referred to as chargers 2032), four developingrollers 2033 a, 2033 b, 2033 c, and 2033 d (hereinafter collectivelyreferred to as developing rollers 2033), and four toner cartridges 2034a, 2034 b, 2034 c, and 2034 d (hereinafter collectively referred to astoner cartridges 2034). The image forming apparatus 2000 furtherincludes a transfer belt 2040, a transfer roller 2042, a fixing roller2050, a pressure roller 2051, a sheet feeding roller 2054, aregistration roller pair 2056, a sheet ejection roller pair 2058, asheet tray 2060, an output tray 2070, a communication controller 2080, adensity detector 2245, four home position sensors 2246 a, 2246 b, 2246c, and 2246 d (hereinafter collectively referred to as home positionsensors 2246), and a printer controller 2090.

The communication controller 2080 controls bidirectional communicationwith an upstream device 100 (e.g., computer) through a network or thelike.

The printer controller 2090 generally controls the foregoing componentsof the image forming apparatus 2000. The printer controller 2090includes, e.g., a central processing unit (CPU), a read only memory(ROM), a random access memory (RAM), and an analog-to-digital (A/D)converter. The ROM holds a program described by codes that the CPUexecutes and various kinds of data that is used for execution of theprogram. The RAM is a working memory. The A/D converter converts analogdata to digital data. The printer controller 2090 controls thecomponents of the image forming apparatus 2000 in response to a requestfrom the upstream device 100 while transmitting image data from theupstream device 100 to the optical scanner 2010.

In the present embodiment, the photoconductor drum 2030 a, the charger2032 a, the developing roller 2033 a, the toner cartridge 2034 a, andthe cleaner 2031 a operate as a set of devices to form a black tonerimage, herein referred to as an image forming station K.

Similarly, the photoconductor drum 2030 b, the charger 2032 b, thedeveloping roller 2033 b, the toner cartridge 2034 b, and the cleaner2031 b operate as a set of devices to form a cyan toner image, hereinreferred to as an image forming station C.

The photoconductor drum 2030 c, the charger 2032 c, the developingroller 2033 c, the toner cartridge 2034 c, and the cleaner 2031 coperate as a set of devices to form a magenta toner image, hereinreferred to as an image forming station M.

The photoconductor drum 2030 d, the charger 2032 d, the developingroller 2033 d, the toner cartridge 2034 d, and the cleaner 2031 doperate as a set of devices to form a yellow toner image, hereinreferred to as an image forming station Y.

Each of the photoconductor drums 2030 functions as an image bearer onwhich a latent image is written according to light emission of a lightsource based on a modulation signal described later. A photosensitivelayer is formed on the surface of each of the photoconductor drums 2030as image bearers. The optical scanner 2010 scans the surface of each ofthe photoconductor drums 2030. The photoconductor drums 2030 a, 2030 b,2030 c, and 2030 d are aligned, having parallel axes, and rotate inidentical directions. In the present embodiment, the photoconductordrums 2030 a, 2030 b, 2030 c, and 2030 d rotates in a clockwisedirection (hereinafter referred to as a direction of rotation R1)illustrated in FIG. 1.

It is to be noted that, in three dimensional orthogonal coordinates XYZ,a direction of an X-axis (hereinafter referred to as a direction X) is adirection in which the four photoconductor drums 2030 are aligned. Adirection of a Y-axis (hereinafter referred to as a direction Y) isparallel to an axial direction of each of the photoconductor drums 2030.

Each of the chargers 2032 uniformly charges the surface of thecorresponding photoconductor drum 2030. According to image data, theoptical scanner 2010 irradiates the charged surface of thephotoconductor drums 2030 with light. Specifically, according to blackimage data, cyan image data, magenta image data, and yellow image data,the optical scanner 2010 irradiates the charged surface of thephotoconductor drums 2030 a, 2030 b, 2030 c, and 2030 d with light beamsmodulated for black, cyan, magenta, and yellow, respectively.Irradiation of the surface of each of the photoconductor drums 2030eliminates the charge of an irradiated portion on the surface of each ofthe photoconductor drums 2030, forming a latent image thereon accordingto the image data. As each of the photoconductor drums 2030 rotates, thelatent image thus formed thereon moves to a position where the latentimage faces the corresponding developing roller 2033. It is to be notedthat a detailed description of a configuration of the optical scanner2010 is deferred.

On each of the photoconductor drums 2030, an area in which the latentimage is written according to the image data is herein referred to as aneffective scanning area, an image forming area, an effective image area,or the like.

The toner cartridge 2034 a accommodates black toner. The black toner issupplied to the developing roller 2033 a. Similarly, the toner cartridge2034 b accommodates cyan toner. The cyan toner is supplied to thedeveloping roller 2033 b. The toner cartridge 2034 c accommodatesmagenta toner. The magenta toner is supplied to the developing roller2033 c. The toner cartridge 2034 d accommodates yellow toner. The yellowtoner is supplied to the developing roller 2033 d.

As each of the developing rollers 2033 rotates, the toner supplied fromthe corresponding toner cartridge 2034 is applied thinly and uniformlyto the surface of the developing roller 2033. When the toner on thesurface of each of the developing rollers 2033 contacts the surface ofthe corresponding photoconductor drum 2030, the toner moves and adheresto the irradiated portion on the surface of the photoconductor drum2030. In other words, each of the developing rollers 2033 allows thetoner to adhere to the latent image formed on the surface of thecorresponding photoconductor drum 2030, rendering the latent imagevisible as a toner image. In the present embodiment, each of thedeveloping rollers 2033 functions as a developing device, which suppliestoner to the latent image written on the image bearer to develop thelatent image into a visible toner image. Thus, a toner image is formedon the surface of each of the photoconductor drums 2030.

The transfer belt 2040 is entrained around a belt rotation mechanism, torotate in a given direction. The surface of each of the photoconductordrums 2030 a. 2030 b, 2030 c, and 2030 d contacts an outercircumferential surface of the transfer belt 2040 at a position oppositea position where the surface of each of the photoconductor drums 2030 a,2030 b, 2030 c, and 2030 d faces the optical scanner 2010. The transferroller 2042 also contacts the outer circumferential surface of thetransfer belt 2040.

As each of the photoconductor drums 2030 rotates, the toner image formedon the surface of each of the photoconductor drums 2030 approaches thetransfer belt 2040. In a primary transfer process, black, cyan, magenta,and yellow toner images are timed to be transferred sequentially ontothe transfer belt 2040 such that the black, cyan, magenta, and yellowtoner images are superimposed one atop another on the transfer belt 2040that rotates in a counterclockwise direction R2 (hereinafter referred toas a direction of rotation R2) illustrated in FIG. 1. Thus, a compositecolor toner image is formed on the transfer belt 2040. As the transferbelt 2040 rotates, the composite color toner image formed on thetransfer belt 2040 approaches the transfer roller 2042.

In a lower portion of the image forming apparatus 2000 is the sheet tray2060 that accommodates recording media. The sheet feeding roller 2054 isdisposed adjacent to the sheet tray 2060. The sheet feeding roller 2054picks up the recording media one at a time from the sheet tray 2060 tofeed the recording medium to the registration roller pair 2056.

Activation of the registration roller pair 2056 is timed to convey therecording medium to an area of contact, herein referred to as asecondary transfer nip, between the transfer belt 2040 and the transferroller 2042 such that the recording medium meets the color toner imageformed on the transfer belt 2040 at the secondary transfer nip.Accordingly, in a secondary transfer process, the color toner image istransferred onto the recording medium from the transfer belt 2040 at thesecondary transfer nip. It is to be noted that, in the presentembodiment, the transfer belt 2040 and the transfer roller 2042 functionas a transfer device to transfer the visible toner image, into which thelatent image is developed by the developing device, onto a recordingmedium. The recording medium bearing the color toner image is thenconveyed to an area of contact, herein referred to as a fixing nip,between the fixing roller 2050 and the pressure roller 2051.

At the fixing nip, the fixing roller 2050 and the pressure roller 2051apply heat and pressure to the recording medium to fix the toner imageonto the recording medium. It is to be noted that, in the presentembodiment, the fixing roller 2050 and the pressure roller 2051 functionas a fixing device to fix the toner image transferred by the transferdevice onto the recording medium. The recording medium bearing the fixedtoner image is conveyed to the sheet ejection roller pair 2058. Thesheet ejection roller pair 2058 ejects the recording medium onto theoutput tray 2070. Thus, a plurality of recording media lies stacked onthe output tray 2070.

Each of the cleaners 2031 removes residual toner from the surface of thecorresponding photoconductor drum 2030. The residual toner is toner thathas failed to be transferred onto the transfer belt 2040 and thereforeis remaining on the surface of the photoconductor drum 2030. Thus, eachof the cleaners 2031 cleans the surface of the correspondingphotoconductor drum 2030. As each of the photoconductor drums 2030rotates, the cleaned surface of each of the photoconductor drums 2030returns to a position where the surface of each of the photoconductordrum 2030 faces the corresponding charger 2032.

The density detector 2245 is disposed on a negative (−) X side of thetransfer belt 2040 in FIG. 1. Specifically, the density detector 2245 isdisposed upstream from the transfer roller 2042 and downstream from thefour photoconductor drums 2030 in the direction of rotation R2 of thetransfer belt 2040.

Referring now to FIGS. 2 and 3, a description is given of the densitydetector 2245.

FIG. 2 is a diagram illustrating relative positions of three opticalsensors 2245 a, 2245 b, and 2245 c, which construct the density detector2245 in the present example. FIG. 3 is a schematic view of the opticalsensor 2245 a and the transfer belt 2040, particularly illustrating aconfiguration of the optical sensor 2245 a.

Specifically, the optical sensor 2245 a is disposed opposite a vicinityof an end portion on a negative (−) Y side within an effective imagearea A on the transfer belt 2040. In other words, the optical sensor2245 a is disposed opposite an end side of the transfer belt 2040 in awidth direction thereof. The optical sensor 2245 c is disposed oppositea vicinity of an end portion on a positive (+) Y side within theeffective image area A on the transfer belt 2040. In other words, theoptical sensor 2245 c is disposed opposite the other end side of thetransfer belt 2040 in the width direction thereof. The optical sensor2245 b is disposed substantially at a middle position between theoptical sensors 2245 a and 2245 c with respect to a main scanningdirection. In other words, the optical sensor 2245 b is disposedopposite a substantially middle position of the transfer belt 2040 inthe width direction thereof. FIG. 2 illustrates Y1, Y2, and Y3 as centerpositions of the optical sensors 2245 a, 2245 b, and 2245 c,respectively, with respect to the main scanning direction, that is, thedirection Y.

FIG. 3 illustrates the configuration of the optical sensor 2245 a, as arepresentative of the optical sensors 2245 a, 2245 b, and 2245 c allhaving identical configurations. The optical sensor 2245 a includes, alight emitting diode (LED) 11, a specularly reflected light receivingdevice 12, and a diffusely reflected light receiving device 13. The LED11 emits light (hereinafter referred to as detection light) toward thetransfer belt 2040. The specularly reflected light receiving device 12receives light specularly reflected from the transfer belt 2040 or atoner pad on the transfer belt 2040. The diffusely reflected lightreceiving device 13 receives light diffusely reflected from the transferbelt 2040 or the toner pad on the transfer belt 2040. Each of thespecularly reflected light receiving device 12 and the diffuselyreflected light receiving device 13 outputs a signal (i.e.,photoelectric conversion signal) corresponding to an amount of lightthus received.

Referring back to FIG. 1, a description is now given of the homeposition sensors 2246. The home position sensor 2246 a detects a homeposition of rotation of the photoconductor drum 2030 a. Similarly, thehome position sensor 2246 b detects a home position of rotation of thephotoconductor drum 2030 b. The home position sensor 2246 c detects ahome position of rotation of the photoconductor drum 2030 c. The homeposition sensor 2246 d detects a home position of rotation of thephotoconductor drum 2030 d.

To provide a fuller understanding of the embodiments of the presentdisclosure, a description is now given of the optical scanner 2010.

Initially with reference to FIGS. 4 through 7, a description is given ofan optical system structure of the optical scanner 2010.

FIG. 4 is a top view of the optical scanner 2010. FIG. 5 is a partialside view of the optical scanner 2010, illustrating an optical path froma light source 2200 a to a polygon mirror 2104 and an optical path froma light source 2200 b to the polygon mirror 2104. FIG. 6 is a partialside view of the optical scanner 2010, illustrating an optical path froma light source 2200 c to the polygon mirror 2104 and an optical pathfrom a light source 2200 d to the polygon mirror 2104. FIG. 7 is apartial side view of the optical scanner, illustrating optical pathsfrom the polygon mirror 2104 to the respective photoconductor drums2030.

As illustrated in FIG. 4, an optical system of the optical scanner 2010includes, e.g., the four light sources 2200 a, 2200 b, 2200 c, and 2200d, four coupling lenses 2201 a, 2201 b, 2201 c, and 2201 d, fouraperture plates 2202 a, 2202 b, 2202 c, and 2202 d, four cylindricallenses 2204 a, 2204 b, 2204 c, and 2204 d, the polygon mirror 2104, fourscanning lenses 2105 a, 2105 b, 2105 c, and 2105 d, and six deflectionmirrors 2106 a, 2106 b, 2106 c, 2106 d, 2108 b, and 2108 c. Theforegoing optical elements are installed at predetermined positions inan optical housing.

It is to be noted that the optical scanner 2010 also includes anelectrical circuit. A description of the electrical circuit of theoptical scanner 2010 is deferred with reference to FIG. 8 and thefollowing drawings.

Each of the light sources 2200 a, 2200 b, 2200 c, and 2200 d includes,e.g., a surface emitting laser array, in which a plurality of lightemitting units are arranged in a two-dimensional array. The lightemitting units of the surface emitting laser array are disposed suchthat the light emitting units are arrayed at equal intervals when allthe light emitting units are orthogonally projected along a virtual linethat extends in a direction corresponding to a sub-scanning direction.Each of the light sources 2200 a, 2200 b, 2200 c, and 2200 d is, e.g., alaser array of vertical cavity surface emitting lasers (VCSELs).

The coupling lens 2201 a is disposed on the optical path of light beamsemitted from the light source 2200 a, rendering the optical beamspassing through the coupling lens 2201 a into parallel light beams.Similarly, the coupling lens 2201 b is disposed on the optical path oflight beams emitted from the light source 2200 b, rendering the opticalbeams passing through the coupling lens 2201 b into parallel lightbeams. The coupling lens 2201 c is disposed on the optical path of lightbeams emitted from the light source 2200 c, rendering the optical beamspassing through the coupling lens 2201 c into parallel light beams. Thecoupling lens 2201 d is disposed on the optical path of light beamsemitted from the light source 2200 d, rendering the optical beamspassing through the coupling lens 2201 d into parallel light beams.

The aperture plate 2202 a has an opening to limit the amount of theparallel light beams coming from the coupling lens 2201 a. Similarly,the aperture plate 2202 b has an opening to limit the amount of theparallel light beams coming from the coupling lens 2201 b. The apertureplate 2202 c has an opening to limit the amount of the parallel lightbeams coming from the coupling lens 2201 c. The aperture plate 2202 dhas an opening to limit the amount of the parallel light beams comingfrom the coupling lens 2201 d.

The cylindrical lens 2204 a images the light beams passing through theopening of the aperture plate 2202 a on a deflection surface of thepolygon mirror 2104 or on an area adjacent thereto, in a direction of aZ-axis (hereinafter referred to as a direction Z). Similarly, thecylindrical lens 2204 b images the light beams passing through theopening of the aperture plate 2202 b on a deflection surface of thepolygon mirror 2104 or on an area adjacent thereto, in the direction Z.The cylindrical lens 2204 c images the light beams passing through theopening of the aperture plate 2202 c on a deflection surface of thepolygon mirror 2104 or on an area adjacent thereto, in the direction Z.The cylindrical lens 2204 d images the light beams passing through theopening of the aperture plate 2202 d on a deflection surface of thepolygon mirror 2104 or on an area adjacent thereto, in the direction Z.

The coupling lens 2201 a, the aperture plate 2202 a, and the cylindricallens 2204 a construct a pre-deflector optical system for the imageforming station K. Similarly, the coupling lens 2201 b, the apertureplate 2202 b, and the cylindrical lens 2204 b construct a pre-deflectoroptical system for the station C. The coupling lens 2201 c, the apertureplate 2202 c, and the cylindrical lens 2204 c construct a pre-deflectoroptical system for the station M. The coupling lens 2201 d, the apertureplate 2202 d, and the cylindrical lens 2204 d construct a pre-deflectoroptical system for the station Y.

The polygon mirror 2104 has a two-story structure, each having afour-sided mirror, rotatable about an axis parallel to the Z-axis. Thefour-sided mirror includes four deflection surfaces. The four-sidedmirror on a first story (i.e., lower story) of the polygon mirror 2104deflects the light beams from the cylindrical lens 2204 b and the lightbeams from the cylindrical lens 2204 c. On the other hand, thefour-sided mirror on a second story (i.e., upper story) of the polygonmirror 2104 deflects the light beams from the cylindrical lens 2204 aand the light beams from the cylindrical lens 2204 d.

The polygon mirror 2104 deflects the light beams from the cylindricallens 2204 a and the light beams from the cylindrical lens 2204 b to the−X side of the polygon mirror 2104, that is, in a negative (−) directionor on a negative (−) side of the X-axis from where the polygon mirror2104 is situated. On the other hand, the polygon mirror 2104 deflectsthe light beams from the cylindrical lens 2204 c and the light beamsfrom the cylindrical lens 2204 d to a positive (+) X side of the polygonmirror 2104, that is, in a positive (+) direction or on a positive (+)side of the X-axis from where the polygon mirror 2104 is situated.

The scanning lenses 2105 a, 2105 b, 2105 c, and 2105 d have opticalpower to condense the light beams to the photoconductor drums 2030 a,2030 b, 2030 c, and 2030 d, respectively, or to an area adjacent to thephotoconductor drums 2030 a, 2030 b, 2030 c, and 2030 d, respectively.The scanning lenses 2105 a, 2105 b, 2105 c, and 2105 d also have opticalpower to move an optical spot on the photoconductor drums 2030 a, 2030b, 2030 c, and 2030 d, respectively, at a constant speed in the mainscanning direction in accordance with rotation of the polygon mirror2104.

The scanning lenses 2105 a and 2105 b are disposed on the −X side of thepolygon mirror 2104. On the other hand, the scanning lenses 2105 c and2105 d are disposed on the +X side of the polygon mirror 2104.

The scanning lens 2105 a rests on the scanning lens 2105 b in thedirection Z. The scanning lens 2105 b is disposed opposite thefour-sided mirror on the first story of the polygon mirror 2104. On theother hand, the scanning lens 2105 a is disposed opposite the four-sidedmirror on the second story of the polygon mirror 2104.

Similarly, the scanning lens 2105 d rests on the scanning lens 2105 c inthe direction Z. The scanning lens 2105 c is disposed opposite thefour-sided mirror on the first story of the polygon mirror 2104. On theother hand, the scanning lens 2105 d is disposed opposite the four-sidedmirror on the second story of the polygon mirror 2104.

The light beams passing through the cylindrical lens 2204 a anddeflected by the polygon mirror 2104 reaches the photoconductor drum2030 a via the scanning lens 2105 a and the deflection mirror 2106 a, toform an optical spot on the photoconductor drum 2030 a. As the polygonmirror 2104 rotates, the optical spot moves in a longitudinal directionof the photoconductor drum 2030 a, that is, the axial direction thereof.Thus, the surface of the photoconductor drum 2030 a is scanned. Thedirection in which the optical spot moves is the “main scanningdirection” on the photoconductor drum 2030 a. The direction of rotationof the photoconductor drum 2030 a (i.e., direction of rotation R1illustrated in FIG. 1) is the “sub-scanning direction” on thephotoconductor drum 2030 a.

Similarly, the light beams passing through the cylindrical lens 2204 band deflected by the polygon mirror 2104 reaches the photoconductor drum2030 b via the scanning lens 2105 b and the deflection mirrors 2106 band 2108 b, to form an optical spot on the photoconductor drum 2030 b.As the polygon mirror 2104 rotates, the optical spot moves in alongitudinal direction of the photoconductor drum 2030 b, that is, theaxial direction thereof. Thus, the surface of the photoconductor drum2030 b is scanned. The direction in which the optical spot moves is the“main scanning direction” on the photoconductor drum 2030 b. Thedirection of rotation of the photoconductor drum 2030 b (i.e., directionof rotation R1 illustrated in FIG. 1) is the “sub-scanning direction” onthe photoconductor drum 2030 b.

Similarly, the light beams passing through the cylindrical lens 2204 cand deflected by the polygon mirror 2104 reaches the photoconductor drum2030 c via the scanning lens 2105 c and the deflection mirrors 2106 cand 2108 c, to form an optical spot on the photoconductor drum 2030 c.As the polygon mirror 2104 rotates, the optical spot moves in alongitudinal direction of the photoconductor drum 2030 c, that is, theaxial direction thereof. Thus, the surface of the photoconductor drum2030 c is scanned. The direction in which the optical spot moves is the“main scanning direction” on the photoconductor drum 2030 c. Thedirection of rotation of the photoconductor drum 2030 c (i.e., directionof rotation R1 illustrated in FIG. 1) is the “sub-scanning direction” onthe photoconductor drum 2030 c.

Similarly, the light beams passing through the cylindrical lens 2204 dand deflected by the polygon mirror 2104 reaches the photoconductor drum2030 d via the scanning lens 2105 d and the deflection mirror 2106 d, toform an optical spot on the photoconductor drum 2030 d. As the polygonmirror 2104 rotates, the optical spot moves in a longitudinal directionof the photoconductor drum 2030 d, that is, the axial direction thereof.Thus, the surface of the photoconductor drum 2030 d is scanned. Thedirection in which the optical spot moves is the “main scanningdirection” on the photoconductor drum 2030 d. The direction of rotationof the photoconductor drum 2030 d (i.e., direction of rotation R1illustrated in FIG. 1) is the “sub-scanning direction” on thephotoconductor drum 2030 d.

The deflection mirrors 2106 a, 2106 b, 2106 c, 2106 d, 2108 b, and 2108c are disposed such that all the optical paths from the polygon mirror2104 to the photoconductor drums 2030 have identical lengths and thatthe light beams enter identical positions of the photoconductor drums2030 at identical angles of incidence.

Optical systems disposed on the optical paths between the polygon mirror2104 and the respective photoconductor drums 2030 are referred to asscanning optical systems. For example, the scanning optical system forthe image forming station K is constructed of, e.g., the scanning lens2105 a and the deflection mirror 2106 a. Similarly, the scanning opticalsystem for the image forming station C is constructed of, e.g., thescanning lens 2105 b and the deflection mirrors 2106 b and 2108 b. Thescanning optical system for the image forming station M is constructedof, e.g., the scanning lens 2105 c and the deflection mirrors 2106 c and2108 c. The scanning optical system for the image forming station Y isconstructed of, e.g., the scanning lens 2105 d and the deflection mirror2106 d. In the present embodiment, each of the scanning optical systemsincludes a single scanning lens 2105. Alternatively, each of thescanning optical systems may include a plurality of scanning lenses2105.

Referring now to FIG. 8, a description is given of an electrical systemof the optical scanner 2010.

FIG. 8 is a block diagram of the electrical system of the opticalscanner 2010.

The electrical system of the optical scanner 2010 includes an interfaceunit 3101, an image processing unit 3102, and a drive control unit 3103as a drive control device.

The interface unit 3101 acquires image data, transmitted by the upstreamdevice 100 (e.g., computer), from the printer controller 2090. Then, theinterface unit 3101 transmits the image data thus acquired to the imageprocessing unit 3102 that follows the interface unit 3101.

In the present example, the interface unit 3101 acquires 8-bit imagedata in red, green, and blue (RGB) format, having a resolution of 1200dots per inch (dpi). The interface unit 3101 transmits the image datathus acquired to the image processing unit 3102.

The image processing unit 3102 functions as an image processor. Theimage processing unit 3102 acquires the image data from the interfaceunit 3101, and converts the image data into color image data appropriatefor the printing system employed. For example, the image processing unit3102 converts the image data in the RGB format (hereinafter simplyreferred to as RGB image data) into image data for a tandem system, thatis, image data in cyan, magenta, yellow, and black format (hereinaftersimply referred to as CMYK image data). In addition to data formatconversion, the image processing unit 3102 performs various kinds ofimage processing.

In the present example, the image processing unit 3102 outputs 1-bit,CMYK image data having a resolution of 2400 dpi. It is to be noted thatthe resolution of the image data outputted by the image processing unit3102 is not limited to 2400 dpi. The resolution of the image dataoutputted by the image processing unit 3102 is herein referred to as afirst resolution.

The image processing unit 3102 also generates tag information. The taginformation indicates whether each of pixels in the image data havingthe first resolution (i.e., 2400 dpi) is a pixel forming text or a line.The tag information is also regarded as information that indicateswhether each of the pixels in the image data is an area in which aspecific object is drawn. In the present example, the specific object isany one of text, a line, and a graphical shape. In the present example,each of the pixels constructing the image data outputted by the imageprocessing unit 3102 includes a first pixel value and a second pixelvalue. The first pixel value indicates image information. The secondpixel value indicates the tag information. In other words, the secondpixel value indicates whether each of the pixels constructing the imagedata is an area in which the specific object is drawn. Hereinafter, theimage data outputted by the image processing unit 3102 is referred to asfirst image data. The image processing unit 3102 transmits the firstimage data thus generated to the drive control unit 3103.

The drive control unit 3103 acquires the first image data from the imageprocessing unit 3102, and converts the first image data into color imagedata having a second resolution, which may be hereinafter referred to assecond image data, appropriate to drive the light sources 2200. It is tobe noted that the second resolution is higher than the first resolution.In the present example, the drive control unit 3103 converts the firstimage data into 1-bit, CMYK image data having a resolution of 4800 dpi.

The drive control unit 3103 modulates the image data having the secondresolution to a clock signal that indicates when a pixel emits light,thereby generating an independent modulation signal for each color. Thedrive control unit 3103 drives each of the light sources 2200 a, 2200 b,2200 c, and 2200 d to emit light according to the modulation signal foreach color. It is to be noted that the drive control unit 3103 mayperform resolution conversion and modulation processing integrally.

The drive control unit 3103 is, e.g., a single, integrated device as onechip disposed adjacent to the light sources 2200 a, 2200 b, 2200 c, and2200 d. The image processing unit 3102 and the interface unit 3101 aredisposed farther from the light sources 2200 a, 2200 b, 2200 c, and 2200d than the drive control unit 3103 is. A cable 3104 couples the imageprocessing unit 3102 to the drive control unit 3103.

In the optical scanner 2010 configured as described above, the lightsources 2200 a, 2200 b, 2200 c, and 2200 d emit light to form latentimages on the surface of the respective photoconductor drums 2030 a,2030 b, 2030 c, and 2030 d according to the respective image data.

Referring now to FIG. 9, a description is given of a structure of theinterface unit 3101.

FIG. 9 is a block diagram of the interface unit 3101.

The interface unit 3101 includes, e.g., a flash memory 3211, a randomaccess memory (RAM) 3212, an interface (IF) circuit 3213, and a centralprocessing unit (CPU) 3214. A bus couples the flash memory 3211, the RAM3212, the IF circuit 3213, and the CPU 3214 to each other.

The flash memory 3211 holds a program that is executed by the CPU 3214and various kinds of data used for execution of the program by the CPU3214. The RAM 3212 is a working, storage area for the CPU 3214 toexecute the program. The IF circuit 3213 performs bidirectionalcommunication with the printer controller 2090.

The CPU 3214 operates in accordance with the program stored in the flashmemory 3211 to control the entire optical scanner 2010. The interfaceunit 3101 configured as described above receives the image data, in thepresent example, 8-bit, RGB image data having a resolution of 1200 dpi,from the printer controller 2090. It is to be noted that the image datathus transmitted and inputted by the printer controller 2090 is hereinreferred to as input image data. Then, the interface unit 3101 transmitsthe input image data to the image processing unit 3102.

Referring now to FIG. 10, a description is given of a structure of theimage processing unit 3102.

FIG. 10 is a block diagram of the image processing unit 3102.

The image processing unit 3102 includes an attribute separator 3220, acolor converter 3221, a black component generator 3222, a gammacorrector 3223, and a position corrector 3224, a gradation processor3225, and a tag generator 3226.

The attribute separator 3220 receives the input image data (i.e., 8-bit,RGB image data having a resolution of 1200 dpi) from the interface unit3101. Attribute information or attribute data is added to each pixel ofthe input image data. The attribute information indicates a type of anobject as a source of the area (i.e., pixel). For example, if the pixelis a part of text, the attribute information indicates an attribute of“text”. Alternatively, if the pixel is a part of a line, the attributeinformation indicates an attribute of “line”. Alternatively, if thepixel is a part of a graphical shape, the attribute informationindicates an attribute of “graphical shape”. Alternatively, if the pixelis a part of a photograph, the attribute information indicates anattribute of “photograph”.

The attribute separator 3220 separates the attribute information andimage data from the input image data. Then, the attribute separator 3220transmits the attribute information and the image data thus separated tothe tag generator 3226. Meanwhile, the attribute separator 3220transmits the image data to the color converter 3221. The image dataoutputted by the attribute separator 3220 is, e.g., 8-bit, RGB imagedata having a resolution of 1200 dpi. On the other hand, the attributedata outputted by the attribute separator 3220 is, e.g., 2-bit datahaving a resolution of 1200 dpi, which is identical to the resolution ofthe image data.

The color converter 3221 converts the 8-bit, RGB image data into 8-bit,CMY image data. Thus, the color converter 3221 generates the 8-bit, CMYimage data. Then, the color converter 3221 transmits the 8-bit, CMYimage data to the black component generator 3222. The black componentgenerator 3222 generates a black component from the CMY image data thusgenerated and transmitted by the color converter 3221, therebygenerating the CMYK image data. Then, the black component generator 3222transmits the CMYK image data to the gamma corrector 3223. The gammacorrector 3223 linearly transforms levels of the respective colors ofthe CMYK image data thus generated and transmitted by the blackcomponent generator 3222, by use of a table or the like. Then, the gammacorrector 3223 transmits the image data thus transformed to the positioncorrector 3224.

The position corrector 3224 removes noise or distortion from the imagedata received from the gamma corrector 3223. In addition, the positioncorrector 3224 magnifies or shifts the image data, for example, tocorrect a position of an image. At this time, the position corrector3224 converts the image data having a resolution of 1200 dpi into imagedata having a resolution of 2400 dpi. Then, the position corrector 3224outputs the CMYK image data having a resolution of 2400 dpi (i.e., firstresolution) in which one pixel is represented by a plurality of bits,which is, in the present example, 8 bits.

The gradation processor 3225 receives the 8-bit, CMYK image data havinga resolution of 2400 dpi from the position corrector 3224. The gradationprocessor 3225 performs digital halftoning, such as dithering or errordiffusion processing, thereby generating 1-bit area modulation data fromthe 8-bit image data.

The tag generator 3226 generates the tag information, which indicateswhether each of the pixels constructing the image data having aresolution of 1200 dpi inputted from the attribute separator 3220 is apixel forming text, a line, or a graphical shape. In other words, asdescribed above, the tag information indicates whether each of thepixels constructing the image data is an area in which a specific objectis drawn. For example, the tag generator 3226 uses the attributeinformation to set an area in which a specific object (any one of text,a line, and a graphical shape) is drawn. Then, the tag generator 3226assigns the tag information to each of pixels included in the area thusset, to indicate that each of the pixels is text, a line, or a graphicalshape. In the present example, the tag information is represented by 1bit. “1” represents tag information indicating that a pixel forms text,a line, or a graphical shape. By contrast, “0” represents taginformation indicating that a pixel does not form text, a line, or agraphical shape. Alternatively, however, “0” may represent the taginformation indicating that a pixel forms text, a line, or a graphicalshape. By contrast, “1” may represent the tag information indicatingthat a pixel does not form text, a line, or a graphical shape. Forexample, if a specific object is drawn by dots, the tag informationrepresented by “1” is assigned to each of black and white pixelsconstructing the specific object.

In the present example, the tag generator 3226 assigns the taginformation indicating that a pixel forms text, a line, or a graphicalshape to black and white pixels accompanied with the attributeinformation indicating an attribute of text, a line, or a graphicalshape. It is to be noted that the black pixel is a pixel of which apixel value is 1 when the number of gradations is reduced to 1 bit.According to data of the black pixel, the light source 2200 emits lightto the photoconductor drum 2030. By contrast, the white pixel is a pixelof which a pixel value is 0 when the number of gradations is reduced to1 bit. According to data of the white pixel, the light source 2200 doesnot emit light to the photoconductor drum 2030.

Now, a description is given of an area to which the tag informationindicating that a pixel forms text, a line, or a graphical shape isassigned. The area is hereinafter referred to as a target area.

In the present embodiment, text, a line, or a graphical shape is thinnedas edge enhancement. In other words, line thinning is performed on thetext, the line, or the graphical shape. Therefore, the tag informationrepresented by “1” (hereinafter simply referred to as tag information 1)is assigned to an area in which text, a line, or a graphical shape isdrawn. That is, the tag information represented by “0” (hereinaftersimply referred to as tag information 0) is assigned to a backgroundarea. In other words, the tag information indicating that a pixel formstext, a line, or a graphical shape is not assigned to the backgroundarea. It is to be noted that the text includes a black text and a whitetext (or outlined text). Similarly, the line includes a black line and awhile line (or outlined line). The graphical shape includes a blackgraphical shape and a while graphical shape (or outlined graphicalshape). For example, as illustrated in FIG. 11, when a specific object(text, a line, or a graphical shape) is drawn by dots, the taginformation 1 is assigned to each of the black and white pixelsconstructing the specific object.

Referring back to FIG. 10, the tag generator 3226 generates andtransmits the tag information to the drive control unit 3103 via theposition corrector 3224 and the gradation processor 3225. As describedabove, the position corrector 3224 converts the image data having aresolution of 1200 dpi into the image data having a higher resolutionof, in this case, 2400 dpi. In addition, the position corrector 3224corrects the position of the image data. The position corrector 3224performs the same processing (resolution conversion and positioncorrection) on the tag information. Since the position corrector 3224converts the tag information having a resolution of 1200 dpi into taginformation having a resolution of 2400 dpi, the tag information can beassigned to each pixel in the image data having a resolution of 2400dpi.

The gradation processor 3225 transmits the 1-bit image information(i.e., area modulation data) having the first resolution (i.e., 2400dpi) and 1-bit tag information having the first resolution (i.e., 2400dpi) to the drive control unit 3103. In the present embodiment, thegradation processor 3225 transmits the image information and the taginformation through a single path. Specifically, the gradation processor3225 transmits 2-bit data having the first resolution (i.e., 2400 dpi)to the drive control unit 3103. A high-order bit of the 2-bit datarepresents the image information (i.e., CMYK) while a low-order bit ofthe 2-bit data represents the tag information.

Thus, the image processing unit 3102 generates and transmits the imagedata (i.e., first image data) having the first resolution (i.e., 2400dpi) to the drive control unit 3103. As described above, the first imagedata includes a plurality of pixels. Each of the plurality of pixelsincludes the first pixel value indicating the image information and thesecond pixel value indicating the tag information. In the presentexample, each of first pixel value and the second pixel value isrepresented by 1 bit.

Referring now to FIGS. 12A through 12D, a description is given of someexamples of the pixels included in the first image data.

FIG. 12A illustrates a while pixel in the background of the first imagedata, as a first example. The tag information 0 is assigned to the whitepixel. FIG. 12B illustrates a black pixel in the background of the firstimage data, as a second example. The tag information 0 is assigned tothe black pixel. FIG. 12C illustrates a white pixel of text, a line, ora graphical shape, as a third example. The tag information 1 is assignedto the white pixel. FIG. 12D illustrates a black pixel of the text, theline, or the graphical shape, as a fourth example. The tag information 1is assigned to the black pixel.

The image processing unit 3102 may be implemented partly or entirely byhardware, or may be implemented by the CPU executing a software program.

Referring now to FIG. 13, a description is given of a structure of thedrive control unit 3103.

FIG. 13 is a block diagram of the drive control unit 3103.

The drive control unit 3103 includes a clock generator 3232, amodulation signal generator 3233, and a light source driver 3234.

The clock generator 3232 generates a clock signal indicating when apixel emits light. The clock signal is a signal that allows image datato be modulated with a resolution corresponding to 4800 dpi.

The modulation signal generator 3233 acquires the first image data fromthe image processing unit 3102. According to the first image data, themodulation signal generator 3233 generates image data having the secondresolution higher than the first resolution. In the present example, themodulation signal generator 3233 generates image data equivalent to1-bit, CMYK image data having a resolution of 4800 dpi, based on 1-bit,CMYK image information and 1-bit tag information each having aresolution of 2400 dpi. Then, the modulation signal generator 3233modulates the image data having the second resolution to the clocksignal, thereby generating a modulation signal to form an image having aresolution of 4800 dpi. The modulation signal is an independentmodulation signal for each color.

The light source driver 3234 receives the modulation signalcorresponding to the image data having the second resolution from themodulation signal generator 3233. The light source driver 3234 driveseach of the light sources 2200 a, 2200 b, 2200 c, and 2200 d accordingto the corresponding modulation signal (i.e., independent modulationsignal for each color) generated and outputted by the modulation signalgenerator 3233. Accordingly, the light source driver 3234 allows each ofthe light sources 2200 a, 2200 b, 2200 c, and 2200 d to perform exposureaccording to the corresponding modulation signal.

Referring now to FIG. 14, a description is given of a structure of themodulation signal generator 3233.

FIG. 14 is a block diagram of the modulation signal generator 3233.

The modulation signal generator 3233 includes a buffer memory 3251, aresolution converter 3252, and a gamma converter 3253.

The buffer memory 3251 accumulates the 2-bit data of the first imagedata having the first resolution (i.e., 2400 dpi) transmitted by theimage processing unit 3102. The 2-bit data includes the high-order bitrepresenting the image information (i.e., CMYK) and the low-order bitrepresenting the tag information. In the present example, the buffermemory 3251 stores data corresponding to a plurality of main scanninglines, that is, a plurality of sets of the image information and the taginformation, of the first image data. It is to be noted that, if theimage data is multi-tone data, the image data may be represented by twoor more bits. The number of bits representing the tag information can bechanged as appropriate. In response to retrieval from the resolutionconverter 3252 that follows the buffer memory 3251, the buffer memory3251 transmits the pixels constructing the first image data thusaccumulated to the resolution converter 3252.

The resolution converter 3252 converts the first image data accumulatedand transmitted by the buffer memory 3251 into the image data having thesecond resolution (equivalent to 1-bit image data having a resolution of4800 dpi) higher than the first resolution. Each pixel of the image datathus converted includes the image information and the tag information.In the present embodiment, the image data thus converted by theresolution converter 3252 is 4-bit data having a resolution of 2400 dpiin the main scanning direction and 1-bit data having a resolution of4800 dpi in the sub-scanning direction. A high-order bit of the 4-bitdata represents the image information (i.e., CMYK) and a low-order bitof the 4-bit data represents the tag information. In FIG. 14, D1represents the main scanning direction while D2 represents thesub-scanning direction.

The resolution converter 3252 subsequently selects target pixels fromthe first image data to execute the resolution conversion for eachtarget pixel. The resolution converter 3252 transmits the image datahaving the second resolution thus converted to the gamma converter 3253.

The gamma converter 3253 receives the image data having the secondresolution from the resolution converter 3252. Then, the gamma converter3253 modulates the image data thus received to the clock signal, andconverts the level of the image data to a level appropriate forcharacteristics of the light source 2200, thereby generating themodulation signal. Then, the gamma converter 3253 transmits themodulation signal thus generated to the light source driver 3234. In thepresent example, the gamma converter 3253 functions as a generator.

FIG. 15 is a diagram of the resolution conversion executed by theresolution converter 3252, illustrating relative positions of bitsrepresenting image information and tag information in the firstresolution (i.e., 2400 dpi), that is, before the resolution isconverted, and relative positions of bits representing the imageinformation and the tag information in a second resolution in the secondresolution (i.e., 4800 dpi), that is, after the resolution is converted.

In the present embodiment, the data having the first resolution isrepresented by 2 bits with a resolution of 2400 dpi in the main scanningdirection D1 and by 1 bit with a resolution of 2400 dpi in thesub-scanning direction D2. The 2-bit data in the main scanning directionD1 includes the high-order bit (bit 1) representing the imageinformation (i.e., CMYK) and the low-order bit (bit 0) representing thetag information.

On the other hand, in the present embodiment, the data having the secondresolution is represented by 4 bits with a resolution of 2400 dpi in themain scanning direction D1 and by 1 bit with a resolution of 4800 dpi inthe sub-scanning direction D2. The 4-bit data in the main scanningdirection D1 includes the high-order bits (bit 3 and bit 2) representingthe image information (i.e., CMYK) and the low-order bits (bit 1 and bit0) representing the tag information. It is to be noted that the datahaving the second resolution is data having a resolution of 2400 dpi inthe main scanning direction D1. Since the number of bits in the mainscanning direction D1 of the data having the second resolution is twicethe number of bits in the main scanning direction D1 of the data havingthe first resolution, the data having the second resolution correspondsto 2-bit data having a resolution of 4800 dpi.

Referring now to FIG. 16, a description is given of a structure of theresolution converter 3252.

FIG. 16 is a block diagram of the resolution converter 3252.

In the present embodiment, the resolution converter 3252 subsequentlyselects the target pixels from the first image data one by one toexecute the processing to convert the resolution (i.e., resolutionconversion as illustrated in FIG. 15) for each target pixel.

As illustrated in FIG. 16, the resolution converter 3252 includes, e.g.,an image matrix acquisition unit 3261, a pattern matching unit 3262, asecond image data converter 3263, a normal pattern converter 3264, and aselector 3268. These functions are implemented by a hardware circuit(e.g., semiconductor integrated circuit).

The image matrix acquisition unit 3261 is an example of an “acquisitionunit”. The image matrix acquisition unit 3261, as an acquisition unit,acquires an image matrix corresponding to an area including a targetpixel and pixels surrounding the target pixel from the first image data.In the present embodiment, the image matrix acquisition unit 3261acquires the image matrix corresponding to an area including a targetpixel and pixels surrounding the target pixel from the buffer memory3251. The image matrix is the image information and also the taginformation of the area including a target pixel and pixels surroundingthe target pixel within the first image data. For example, the imagematrix is the image information and also the tag information of arectangle area centering a target pixel within the first image data. Inthe present embodiment, the image matrix is the image information andalso the tag information of an area constructed of 3×3 pixels centeringa target pixel within the first image data. In other words, the imagematrix is a partial image of the first image data. The partial image,having the first resolution, is the area constructed of 3×3 pixelscentering a target pixel within the first image data. Each of the pixelsconstructing the image matrix is represented by 2-bit information thatincludes the first pixel value indicating the image information and thesecond pixel value indicating the tag information. The size of the imagematrix is determined based on the size of a detection pattern that isused for pattern matching performed by the pattern matching unit 3262,described later. In the present embodiment, as illustrated in FIG. 17,the image matrix is a pattern of pixels aligned in a 3×3 matrix.

The pattern matching unit 3262 performs pattern matching to determinewhether one or more detection patterns match the image matrix acquiredby the image matrix acquisition unit 3261. Each of the one or moredetection patterns includes a plurality of pixels. Each of the pluralityof pixels includes the first pixel value indicating the imageinformation and the second pixel value indicating the tag information.Each of the one or more detection patterns is a pattern to detect apixel forming an edge portion in which each of the first pixel value andthe second pixel value varies between pixels.

For example, the pattern matching unit 3262 determines that the targetpixel forms the edge portion between a specific object (i.e., line,text, or graphical shape) and a background, if the location of the imageinformation and the tag information within the image matrix matches anyof a plurality of detection patterns registered in advance. If not, thepattern matching unit 3262 determines that the target pixel does notform the edge portion between the specific object and the background.

Referring now to FIGS. 18A through 18C, a description is given of someexamples of the detection pattern as a first type of detection pattern.

FIG. 18A is a diagram of a first example of the detection pattern. FIG.18B is a second example of the detection pattern. FIG. 18C is a diagramof a third example of the detection pattern.

Such examples of the detection pattern as illustrated in FIGS. 18Athrough 18C are used to detect a pixel forming an edge portion that is aboundary between a black pixel of text, a line, or a graphical shape anda white pixel of a background. In the edge portion, each of the firstpixel value and the second pixel value varies between pixels, from oneof “0” and “1” to the other. FIGS. 18A and 18B illustrate examples ofthe detection pattern to detect a pixel forming a corner of the specificobject (i.e., line, text, or graphical shape). FIG. 18C illustratesexamples of the detection pattern to detect a pixel forming an edgeportion of the specific object (i.e., line, text, or graphical shape),that is, a boundary between the specific object and the background. InFIGS. 18A through 18C, a pixel corresponding to the target pixel is ablack pixel located in the center of the matrix in each example of thedetection pattern. As illustrated in FIGS. 18A through 18C, the taginformation 1 is assigned to the black pixel corresponding to the targetpixel.

Referring back to FIG. 16, if the pattern matching unit 3262 determinesthat the target pixel forms the edge portion (i.e., boundary) betweenthe specific object and the background, the pattern matching unit 3262transmits a matching signal MS to the second image data converter 3263to identify the location of the image information and the taginformation within the image matrix. By contrast, if the patternmatching unit 3262 determines that the target pixel does not form theedge portion between the specific object and the background, the patternmatching unit 3262 does not transmit the matching signal MS to thesecond image data converter 3263.

If the image matrix matches any of the one or more detection patterns,the second image data converter 3263 performs the edge enhancement onthe target pixel and the resolution conversion to convert the firstresolution into the second resolution higher than the first resolution,to convert the target pixel into the second image data (hereinafterreferred to as a first image processing pattern). The edge enhancementis herein line thinning. The second image data converter 3263 performsimage processing associated with the one or more detection patterns thatmatch the image matrix, with reference to image processing informationin which image processing corresponding to the line thinning and theresolution conversion is associated with each of the one or moredetection patterns. In the present example, if the second image dataconverter 3263 receives the matching signal MS from the pattern matchingunit 3262, the second image data converter 3263 performs imageprocessing associated with the detection pattern corresponding to thelocation of the image information and the tag information indicated bythe matching signal MS thus received.

After performing the image processing associated with the detectionpattern that matches the image matrix, the second image data converter3263 outputs the first image processing pattern acquired by the imageprocessing to the selector 3268 together with an enable signal.Alternatively, for example, the pattern matching unit 3262 may outputthe enable signal to the selector 3268 after determining that the imagematrix matches any of the one or more detection patterns. In short, theselector 3268 receives the enable signal after the second image dataconverter 3263 performs conversion.

For example, if the image matrix matches a detection pattern illustratedin FIG. 19A corresponding to an upper-left detection pattern of FIG.18A, and if the second image data converter 3263 performs imageprocessing associated with the detection pattern of FIG. 19A, the targetpixel included in the image matrix is converted into the target pixelillustrated in FIG. 19B. FIGS. 20A through 30B are diagrams similar tothe diagrams of FIGS. 19A and 19B. Specifically, FIG. 20A illustrates adetection pattern corresponding to an upper-right detection pattern ofFIG. 18A. If the second image data converter 3263 performs imageprocessing associated with the detection pattern of FIG. 20A, the targetpixel included in the image matrix is converted into the target pixelillustrated in FIG. 20B. FIG. 21A illustrates a detection patterncorresponding to a lower-left detection pattern of FIG. 18A. If thesecond image data converter 3263 performs image processing associatedwith the detection pattern of FIG. 21A, the target pixel included in theimage matrix is converted into the target pixel illustrated in FIG. 21B.FIG. 22A illustrates a detection pattern corresponding to a lower-rightdetection pattern of FIG. 18A. If the second image data converter 3263performs image processing associated with the detection pattern of FIG.22A, the target pixel included in the image matrix is converted into thetarget pixel illustrated in FIG. 22B.

FIG. 23A illustrates a detection pattern corresponding to an upper-leftdetection pattern of FIG. 18B. If the second image data converter 3263performs image processing associated with the detection pattern of FIG.23A, the target pixel included in the image matrix is converted into thetarget pixel illustrated in FIG. 23B. FIG. 24A illustrates a detectionpattern corresponding to an upper-right detection pattern of FIG. 18B.If the second image data converter 3263 performs image processingassociated with the detection pattern of FIG. 24A, the target pixelincluded in the image matrix is converted into the target pixelillustrated in FIG. 24B. FIG. 25A illustrates a detection patterncorresponding to a lower-left detection pattern of FIG. 18B. If thesecond image data converter 3263 performs image processing associatedwith the detection pattern of FIG. 25A, the target pixel included in theimage matrix is converted into the target pixel illustrated in FIG. 25B.FIG. 26A illustrates a detection pattern corresponding to a lower-rightdetection pattern of FIG. 18B. If the second image data converter 3263performs image processing associated with the detection pattern of FIG.26A, the target pixel included in the image matrix is converted into thetarget pixel illustrated in FIG. 26B.

FIG. 27A illustrates a detection pattern corresponding to an upper-leftdetection pattern of FIG. 18C. If the second image data converter 3263performs image processing associated with the detection pattern of FIG.27A, the target pixel included in the image matrix is converted into thetarget pixel illustrated in FIG. 27B. FIG. 28A illustrates a detectionpattern corresponding to an upper-right detection pattern of FIG. 18C.If the second image data converter 3263 performs image processingassociated with the detection pattern of FIG. 28A, the target pixelincluded in the image matrix is converted into the target pixelillustrated in FIG. 28B. FIG. 29A illustrates a detection patterncorresponding to a lower-left detection pattern of FIG. 18C. If thesecond image data converter 3263 performs image processing associatedwith the detection pattern of FIG. 29A, the target pixel included in theimage matrix is converted into the target pixel illustrated in FIG. 29B.FIG. 30A illustrates a detection pattern corresponding to a lower-rightdetection pattern of FIG. 18C. If the second image data converter 3263performs image processing associated with the detection pattern of FIG.30A, the target pixel included in the image matrix is converted into thetarget pixel illustrated in FIG. 30B.

In the present embodiment, the priority is established in advancebetween three groups formed by FIGS. 18A through 18C, respectively. Forexample, the group of FIG. 18A precedes the group of FIG. 18B, and thegroup of FIG. 18B precedes the group of FIG. 18C. If a plurality ofgroups includes a detection pattern that matches the image matrix, thesecond image data converter 3263 may perform image processing associatedwith the detection pattern belonging to one of the groups taking toppriority.

Thus, if the target pixel forms the edge portion (i.e., boundary)between the specific object and the background, the second image dataconverter 3263 converts the image information and the tag information ofthe target pixel into the image information and the tag information,each having the second resolution, corresponding to the detectionpattern determined corresponding to the location within the imagematrix. In the present embodiment, the second image data converter 3263outputs the data of 4-bit data having a resolution of 2400 dpi in themain scanning direction and 1-bit data having a resolution of 4800 dpiin the sub-scanning direction, as the image information and the taginformation each having the second resolution, that is, as the firstimage processing pattern.

Referring now to FIGS. 31A through 31C, a description is given ofexamples of the line thinning and the resolution conversion.

FIG. 31A is a diagram of the line thinning and the resolution conversionperformed on a simple, quadrangular solid image.

The left image of FIG. 13A is an image before the line thinning and theresolution conversion is performed. The background is constructed ofwhite pixels to which the tag information 0 is assigned. The taginformation 0 indicates that the pixels, in this case, the white pixels,do not construct an area in which the specific object is drawn. Bycontrast, black pixels to which the tag information 1 is assignedconstruct a target area that is the area in which the specific object isdrawn. The image processing associated with the detection pattern thatmatches the image matrix is performed as described above. That is, theline thinning and the resolution conversion are performed on a pixelforming the edge portion (i.e., boundary) between the background and thespecific object.

FIG. 31B is a diagram of the line thinning and the resolution conversionperformed on a specific object drawn by dots.

In the present case, the target area includes black and white pixels.The tag information 1 is assigned to each of the black and white pixelswithin the target area. The detection pattern that is used for thepattern matching performed by the pattern matching unit 3262 includes aplurality of pixels each including the 1-bit first pixel valueindicating the image information and the 1-bit second pixel valueindicating the tag information. That is, each of the first pixel valueand the second pixel value is represented by 1 bit. The detectionpattern is a pattern to detect a pixel forming an edge portion in whicheach of the first pixel value and the second pixel value varies betweenpixels. Therefore, the pattern matching unit 3262 does not detect aboundary between a black pixel and a white pixel within the target area.Instead, the pattern matching unit 3262 detects the edge portion (i.e.,boundary) between the target area and the background in the patternmatching by use of the detection pattern. Accordingly, the line thinningis performed only on the pixel forming the edge portion (i.e., boundary)between the target area and the background. That is, in the presentexample, the line thinning is performed only on each of the black pixelsto which the tag information 1 is assigned. In other words, the linethinning is not performed on a pixel forming the boundary between ablack pixel and a white pixel within the target area. That is, thedensity of the specific object is not affected.

FIG. 31C is a diagram of an image after the line thinning is performedwithout using a detection pattern. Before the line thinning isperformed, a pixel forming an edge portion (i.e., boundary) between ablack pixel and a white pixel is simply detected without using thedetection pattern.

Since the line thinning is performed on a pixel within the target area,the density of dots in the image of FIG. 31C is changed, compared to theimage of FIG. 31B. That is, the density of the specific object ischanged.

Thus, in a typical way of line thinning on text or a line drawn by dots,the line thinning is performed not only on the boundary between theobject and the background but also on the boundary between black andwhite in the object drawn by dots. As a consequence, the image densitychanges unexpectedly.

Hence, according to the present embodiment, the edge enhancement can beperformed without causing unexpected changes in image density.

As described above, in the present embodiment, the pattern matching unit3262 determines whether one or more detection patterns match the imagematrix including a target pixel. Each of the one or more detectionpatterns includes a plurality of pixels. Each of the plurality of pixelsincludes the first pixel value indicating the image information and thesecond pixel value indicating the tag information. In other words, thesecond pixel value indicates whether each of the plurality of pixels isan area in which the specific object is drawn. Each of the one or moredetection patterns is a pattern to detect a pixel forming an edgeportion in which each of the first pixel value and the second pixelvalue varies between pixels. Accordingly, the pixel forming the edgeportion (i.e., boundary) between the specific object and the background,can be detected. In the present example, the pixel that can be detectedis a black pixel to which the tag information 1 is assigned. The linethinning is performed only on the pixel thus detected. That is, evenwhen a specific object is drawn by dots, for example, a pixel forming anedge portion (i.e., boundary) between a black pixel and a white pixelillustrating the specific object is not detected as an object to beprocessed. In short, the line thinning is not performed on the pixelforming the edge portion (i.e., boundary) between the black pixel andthe white pixel within the specific object. Accordingly, the linethinning (i.e., edge enhancement) can be performed without affecting thedensity of the specific object. In other words, the edge enhancement canbe performed without causing unexpected changes in image density.

The examples of the detection pattern described above as illustrated inFIGS. 18A though 18C are used to detect a pixel forming an edge portion(i.e., boundary) between a black pixel of text, a line, or a graphicalshape and a white pixel of the background. Alternatively, examples ofthe detection pattern as illustrated in FIGS. 32A through 32C may beused to detect a pixel forming an edge portion (i.e., boundary) betweena white pixel of text, a line, or a graphical shape and a black pixel ofthe background.

Referring now to FIGS. 32A through 32C, a description is given of someexamples of the detection pattern as a second type of detection pattern.

FIG. 32A is a diagram of a first example of the detection pattern. FIG.32B is a second example of the detection pattern. FIG. 32C is a diagramof a third example of the detection pattern.

Specifically, FIGS. 32A and 32B illustrate examples of the detectionpattern to detect a pixel forming a corner of the specific object (i.e.,line, text, or graphical shape). FIG. 32C illustrates examples of thedetection pattern to detect a pixel forming an edge portion of thespecific object (i.e., line, text, or graphical shape), that is, aboundary between the specific object and the background.

In FIGS. 32A through 32C, a pixel corresponding to the target pixel(i.e., pixel subjected to edge enhancement) is a black pixel located inthe center of the matrix in each example of the detection pattern. Asillustrated in FIGS. 32A through 32C, the tag information 0 is assignedto the black pixel corresponding to the target pixel.

For example, if the image matrix matches a detection pattern illustratedin FIG. 33A corresponding to an upper-left detection pattern of FIG.32A, and if the second image data converter 3263 performs imageprocessing associated with the detection pattern of FIG. 33A, the targetpixel included in the image matrix is converted into the target pixelillustrated in FIG. 33B. FIGS. 34A through 44B are diagrams similar tothe diagrams of FIGS. 33A and 33B. Specifically, FIG. 34A illustrates adetection pattern corresponding to an upper-right detection pattern ofFIG. 32A. If the second image data converter 3263 performs imageprocessing associated with the detection pattern of FIG. 34A, the targetpixel included in the image matrix is converted into the target pixelillustrated in FIG. 34B. FIG. 35A illustrates a detection patterncorresponding to a lower-left detection pattern of FIG. 32A. If thesecond image data converter 3263 performs image processing associatedwith the detection pattern of FIG. 35A, the target pixel included in theimage matrix is converted into the target pixel illustrated in FIG. 35B.FIG. 36A illustrates a detection pattern corresponding to a lower-rightdetection pattern of FIG. 32A. If the second image data converter 3263performs image processing associated with the detection pattern of FIG.36A, the target pixel included in the image matrix is converted into thetarget pixel illustrated in FIG. 36B.

FIG. 37A illustrates a detection pattern corresponding to an upper-leftdetection pattern of FIG. 32B. If the second image data converter 3263performs image processing associated with the detection pattern of FIG.37A, the target pixel included in the image matrix is converted into thetarget pixel illustrated in FIG. 37B. FIG. 38A illustrates a detectionpattern corresponding to an upper-right detection pattern of FIG. 32B.If the second image data converter 3263 performs image processingassociated with the detection pattern of FIG. 38A, the target pixelincluded in the image matrix is converted into the target pixelillustrated in FIG. 38B. FIG. 39A illustrates a detection patterncorresponding to a lower-left detection pattern of FIG. 32B. If thesecond image data converter 3263 performs image processing associatedwith the detection pattern of FIG. 39A, the target pixel included in theimage matrix is converted into the target pixel illustrated in FIG. 39B.FIG. 40A illustrates a detection pattern corresponding to a lower-rightdetection pattern of FIG. 32B. If the second image data converter 3263performs image processing associated with the detection pattern of FIG.40A, the target pixel included in the image matrix is converted into thetarget pixel illustrated in FIG. 40B.

FIG. 41A illustrates a detection pattern corresponding to an upper-leftdetection pattern of FIG. 32C. If the second image data converter 3263performs image processing associated with the detection pattern of FIG.41A, the target pixel included in the image matrix is converted into thetarget pixel illustrated in FIG. 41B. FIG. 42A illustrates a detectionpattern corresponding to an upper-right detection pattern of FIG. 32C.If the second image data converter 3263 performs image processingassociated with the detection pattern of FIG. 42A, the target pixelincluded in the image matrix is converted into the target pixelillustrated in FIG. 42B. FIG. 43A illustrates a detection patterncorresponding to a lower-left detection pattern of FIG. 32C. If thesecond image data converter 3263 performs image processing associatedwith the detection pattern of FIG. 43A, the target pixel included in theimage matrix is converted into the target pixel illustrated in FIG. 43B.FIG. 44A illustrates a detection pattern corresponding to a lower-rightdetection pattern of FIG. 32C. If the second image data converter 3263performs image processing associated with the detection pattern of FIG.44A, the target pixel included in the image matrix is converted into thetarget pixel illustrated in FIG. 44B.

In the present embodiment, the priority is established in advancebetween three groups formed by FIGS. 32A through 32C, respectively. Forexample, the group of FIG. 32A precedes the group of FIG. 32B, and thegroup of FIG. 32B precedes the group of FIG. 32C. If a plurality ofgroups includes a detection pattern that matches the image matrix, thesecond image data converter 3263 may perform image processing associatedwith the detection pattern belonging to one of the groups taking toppriority.

Referring now to FIG. 45, a description is given of an example of imageprocessing.

FIG. 45 is a diagram of image processing by which an outlined quadrangleis drawn as a specific object on a dithering-pattern background.

In the present example, the tag information 1 is assigned to each ofwhite pixels constructing the outlined graphical shape (i.e., outlinedquadrangle). By contrast, the tag information 0 is assigned to each ofblack and white pixels constructing the background that includes adithering pattern. As described above, the detection pattern that isused for the pattern matching performed by the pattern matching unit3262 includes a plurality of pixels each including the 1-bit first pixelvalue indicating the image information and the 1-bit second pixel valueindicating the tag information. That is, each of the first pixel valueand the second pixel value is represented by 1 bit. The detectionpattern is a pattern to detect a pixel forming an edge portion in whicheach of the first pixel value and the second pixel value varies betweenpixels. Therefore, the pattern matching unit 3262 does not detect aboundary between a black pixel and a white pixel within the background.Instead, the pattern matching unit 3262 detects the edge portion (i.e.,boundary) between the target area in which the outlined graphical shapeis drawn and the background (i.e., black pixels in the ditheringpattern) in the pattern matching by use of the detection pattern.Accordingly, the line thinning is performed only on the pixel formingthe edge portion (i.e., boundary) between the target area and thebackground. That is, in the present example, the line thinning isperformed only on each of the black pixels to which the tag information0 is assigned. Specifically, the line thinning includes removal of theblack pixels to which the tag information 0 is assigned, to expand theoutlined graphical shape. In other words, the line thinning is notperformed on a pixel forming the boundary between a black pixel and awhite pixel within the background. Accordingly, the edge enhancement canbe performed without causing unexpected changes in image density.

Referring back to FIG. 16, a description is now resumed of the structureof the resolution converter 3252. The normal pattern converter 3264 isan example of a “third image data converter”. The normal patternconverter 3264, as a third image data converter, performs the resolutionconversion on the target pixel to convert the target pixel into imagedata having the second resolution (herein referred to as third imagedata). Hereinafter, the image data acquired by the resolution conversionperformed by the normal pattern converter 3264 is referred to as anormal pattern. In the present embodiment, the normal pattern converter3264 outputs the normal pattern, on which the line thinning or smoothingprocessing is not performed. The normal pattern is represented by 4-bitdata having a resolution of 2400 dpi in the main scanning direction and1-bit data having a resolution of 4800 dpi in the sub-scanningdirection, as the image information and the tag information each havingthe second resolution. The normal pattern converter 3264 transmits thenormal pattern to the selector 3268.

The selector 3268 is an example of a “selector”. The selector 3268, as aselector, selects either of the first image processing pattern (i.e.,second image data) received from the second image data converter 3263and the normal pattern (i.e., third image data) received from the normalpattern converter 3264. In the present example, the selector 3268selects the first image processing pattern if the selector 3268 receivesthe enable signal described above. By contrast, if the selector 3268does not receive the enable signal, the selector 3268 selects the normalpattern.

The resolution converter 3252 having a configuration described aboveconverts image data having the first resolution into image data havingthe second resolution. In addition, the resolution converter 3252performs image processing on an edge of text, a line, or the like. Forexample, the resolution converter 3252 can thin a black text or a blackline. Alternatively, the resolution converter 3252 can thicken anoutlined text or an outlined line. In this case, the resolutionconverter 3252 may thin a black line.

Referring now to FIG. 46, a description is given of a flow of processingperformed by the resolution converter 3252.

FIG. 46 is a flowchart of an example of processing performed by theresolution converter 3252 when a target pixel is selected, that is, whenthe image matrix acquisition unit 3261 acquires an image matrixincluding the target pixel.

FIG. 46 illustrates a first path and a second path parallel to eachother. The first path is processing performed by the pattern matchingunit 3262 and the second image data converter 3263. The second path isprocessing performed by the normal pattern converter 3264. Sincecontents of steps are described in detail as above, a brief descriptionis now given below.

Initially, a description is given of the first path. In step S101, thepattern matching unit 3262 determines whether the target pixel forms anedge portion (i.e., boundary) between a specific object and abackground. Specifically, as described above, the pattern matching unit3262 determines whether one or more detection patterns match the imagematrix acquired by the image matrix acquisition unit 3261, therebydetermining whether the target pixel included in the image matrix formsthe edge portion (i.e., boundary) between the specific object and thebackground.

If the pattern matching unit 3262 determines that the target pixel formsthe edge portion (i.e., boundary) between the specific object and thebackground (YES in S101), then, the second image data converter 3263converts the target pixel into the first image processing pattern andoutputs an enable signal in step S102. Then, the process goes to stepS104 described later. By contrast, if the pattern matching unit 3262determines that the target pixel does not form the edge portion (i.e.,boundary) between the specific object and the background (NO in S101),then, the process goes to step S104.

Now, a description is given of the second path.

The normal pattern converter 3264 converts the target pixel into thenormal pattern in step S103. Then, the process goes to step S104.

In step S104, the selector 3268 selects and outputs an image or imagedata. As described above, the selector 3268 selects and outputs thefirst image processing pattern if the selector 3268 receives the enablesignal. By contrast, if the selector 3268 does not receive the enablesignal, the selector 3268 selects and outputs the normal pattern.

As described above, in the present embodiment, the pattern matching unit3262 determines whether one or more detection patterns match the imagematrix including a target pixel. Each of the one or more detectionpatterns includes a plurality of pixels. Each of the plurality of pixelsincludes the first pixel value indicating the image information and thesecond pixel value indicating the tag information. In other words, thesecond pixel value indicates whether each of the plurality of pixels isan area in which the specific object is drawn. Each of the one or moredetection patterns is a pattern to detect a pixel forming an edgeportion in which each of the first pixel value and the second pixelvalue varies between pixels. Accordingly, the pixel forming the edgeportion (i.e., boundary) between the specific object and the backgroundcan be detected. The line thinning is performed only on the pixel thusdetected. That is, even when a specific object is drawn by dots, forexample, a pixel forming an edge portion (i.e., boundary) between ablack pixel and a white pixel illustrating the specific object is notdetected as an object to be processed. In short, the line thinning isnot performed on the pixel forming the edge portion (i.e., boundary)between the black pixel and the white pixel within the specific object.Accordingly, the line thinning (i.e., edge enhancement) can be performedwithout affecting the density of the specific object. Accordingly, theedge enhancement can be performed without causing unexpected changes inimage density.

Referring now to FIGS. 47A through 51, a description is given of avariation of the first embodiment.

The intensity of the line thinning can be changed as appropriate.

FIGS. 47A and 47B illustrate examples of image processing including theline thinning and the resolution conversion performed on pixelsconstructing edge portions (i.e., boundaries) between the specificobject and the background in a lateral direction. The line thinning isperformed with different intensities between FIGS. 47A and 47B. FIGS.47C and 47D illustrate examples of image processing including the linethinning and the resolution conversion performed on pixels constructingedge portions (i.e., boundaries) between the specific object and thebackground in a vertical direction. The line thinning is performed withdifferent intensities between FIGS. 47C and 47D.

In addition, for example, the intensity of the line thinning associatedwith the detection pattern to detect a pixel forming the edge portion inthe lateral direction can be different from the intensity of the linethinning associated with the detection pattern to detect a pixel formingthe edge portion in the vertical direction.

In the first embodiment described above, a far-end pixel of the edgeportion is defined as a pixel subjected to the edge enhancement (i.e.,target pixel). Alternatively, for example, the far-end pixel and a pixeladjacent to and disposed inside the far-end pixel, that is, in adirection away from the edge portion, may be defined as pixels subjectedto the edge enhancement. It is to be noted that the far-end pixel isherein referred to as a far-edge pixel. The pixel adjacent to anddisposed inside the far-end pixel is herein referred to as an adjacentedge pixel. For example, as detection patterns to detect a pixel formingan edge portion (i.e., boundary) between a black pixel (i.e., text,line, or graphical shape) and a white pixel (i.e., background), adetection pattern to detect the far-edge pixel as illustrated in FIG.48A and a detection pattern to detect the adjacent edge pixel asillustrated in FIG. 48B may be prepared in advance. Each of FIGS. 48Aand 48B illustrates a 7×7 matrix pattern. However, the size of thematrix pattern is not limited to the 7×7 matrix pattern. The size of thedetection pattern (i.e., size of the image matrix) can be changed asappropriate.

Alternatively, as detection patterns to detect a pixel forming an edgeportion (i.e., boundary) between a white pixel (i.e., text, line, orgraphical shape) and a black pixel (i.e., background), a detectionpattern to detect the far-edge pixel as illustrated in FIG. 49A and adetection pattern to detect the adjacent edge pixel as illustrated inFIG. 49B may be prepared in advance. Each of FIGS. 49A and 49Billustrates a 7×7 matrix pattern. However, the size of the matrixpattern is not limited to the 7×7 matrix pattern. The size of thedetection pattern (i.e., size of the image matrix) can be changed asappropriate.

The intensity of the line thinning to thin a black text line may bedifferent from the intensity of the line thinning to thin black pixelsof the background when a white text line is thickened.

FIG. 50 is a diagram of an example of image processing including theline thinning performed on input image data (i.e., first image data)including pixels forming an edge portion, in this case, in the lateraldirection, between a black text line and a background (i.e., whitepixels). Specifically, each block of pixels illustrated on a left sideof FIG. 50 includes a pixel (i.e., black target pixel) forming the edgeportion (i.e., boundary) between the black text line and the backgroundin the lateral direction. The image processing is performed on thetarget black pixel.

By contrast, FIG. 51 is a diagram of an example of image processingincluding the line thinning performed on input image data (i.e., firstimage data) including pixels forming an edge portion, in this case, inthe lateral direction, between a white text line and a background (i.e.,black pixels). Specifically, each block of pixels illustrated on a leftside of FIG. 51 includes a pixel (i.e., black target pixel) forming theedge portion (i.e., boundary) between the white text line and thebackground in the lateral direction. The image processing is performedon the target black pixel.

Now, a description is given of a second embodiment of the presentdisclosure.

Any description of the second embodiment redundant with theabove-description of the first embodiment is herein omitted unlessotherwise required.

Referring now to FIG. 52, a description is given of a structure of aresolution converter 3252A according to the second embodiment.

FIG. 52 is a block diagram of the resolution converter 3252A.

As illustrated in FIG. 52, the pattern matching unit 3262 of the presentembodiment includes, e.g., a first pattern matching unit 3301 and asecond pattern matching unit 3302. The second image data converter 3263includes a first converter 3401 and a second converter 3402.

Initially, a description is given of the first pattern matching unit3301 and the first converter 3401. The first pattern matching unit 3301determines whether one or more first detection patterns match the imagematrix acquired by the image matrix acquisition unit 3261. Each of theone or more first detection patterns is a pattern to detect a pixelforming the edge portion, that is, the boundary between the specificobject and the background. In the present embodiment, the function ofthe first pattern matching unit 3301 is identical to the function of thepattern matching unit 3262 of the first embodiment described above. Ifthe first pattern matching unit 3301 determines that the target pixelforms the edge portion, the first pattern matching unit 3301 transmits afirst matching signal MS1 to the first converter 3401 to identify thelocation of the image information and the tag information within theimage matrix. It is to be noted that the first matching signal MS1 isequivalent to the matching signal MS of the first embodiment describedabove. By contrast, if the first pattern matching unit 3301 determinesthat the target pixel does not form the edge portion, the first patternmatching unit 3301 does not transmit the first matching signal MS1 tothe first converter 3401.

If the image matrix matches any of the one or more first detectionpatterns, the first converter 3401 performs the line thinning, as theedge enhancement, and the resolution conversion on the target pixel toconvert the target pixel into the second image data (i.e., first imageprocessing pattern). In the present embodiment, the function of thefirst converter 3401 is equivalent to the function of the second imagedata converter 3263 of the first embodiment described above. In thepresent example, if the first converter 3401 receives the first matchingsignal MS1 from the first pattern matching unit 3301, the firstconverter 3401 performs image processing associated with the firstdetection pattern corresponding to the location of the image informationand the tag information indicated by the first matching signal MS1 thusreceived. After performing the image processing associated with thefirst detection pattern that matches the image matrix, the firstconverter 3401 outputs the first image processing pattern acquired bythe image processing to the selector 3268 together with a first enablesignal. It is to be noted that first enable signal is equivalent to theenable signal of the first embodiment described above.

Now, a description is given of the second pattern matching unit 3302 andthe second converter 3402.

The second pattern matching unit 3302 determines whether one or moresecond detection patterns match the image matrix acquired by the imagematrix acquisition unit 3261. Each of the one or more second detectionpatterns is a pattern to detect a pixel forming a step (i.e.,difference) and the edge portion described above. For example, thesecond pattern matching unit 3302 determines that the target pixel formsthe step and the edge portion described above, that is, an edge portionof a difference between the specific object and the background, if thelocation of the image information and the tag information within theimage matrix matches any of a plurality of second patterns registered inadvance. If not, the second pattern matching unit 3302 determines thatthe target pixel does not form the step and the edge portion describedabove.

If the second pattern matching unit 3302 determines that the targetpixel forms the step and the edge portion described above, the secondpattern matching unit 3302 transmits a second matching signal MS2 to thesecond converter 3402 to identify the location of the image informationand the tag information within the image matrix. By contrast, if thesecond pattern matching unit 3302 determines that the target pixel doesnot form the step and the edge portion described above, the secondpattern matching unit 3302 does not transmit the second matching signalMS2 to the second converter 3402.

If the image matrix matches any of the one or more second detectionpatterns, the second converter 3402 performs the line thinning and thesmoothing processing, as the edge enhancement, and the resolutionconversion on the target pixel to convert the target pixel into thesecond image data. It is to be noted that the smoothing processing isprocessing to level the step or to equalize the difference. The secondconverter 3402 performs image processing associated with the one or moresecond detection patterns that match the image matrix, with reference tosecond image processing information in which image processingcorresponding to the line thinning, the smoothing processing, and theresolution conversion is associated with each of the one or more seconddetection patterns. In the present example, if the second converter 3402receives the second matching signal MS2 from the second pattern matchingunit 3302, the second converter 3402 performs image processingassociated with the second detection pattern corresponding to thelocation of the image information and the tag information indicated bythe second matching signal MS2. FIG. 52 illustrates a second imageprocessing pattern, which is the image data having the second resolution(i.e., example of the second image data) acquired by the resolutionconversion performed by the second converter 3402. After performing theimage processing associated with the second detection pattern thatmatches the image matrix, the second converter 3402 outputs the secondimage processing pattern acquired by the image processing to theselector 3268 together with a second enable signal. Alternatively, forexample, the second pattern matching unit 3302 may output the secondenable signal to the selector 3268 after determining that the imagematrix matches any of the one or more second detection patterns. Inshort, the selector 3268 receives the enable signal after the secondconverter 3402 performs conversion.

For example, FIG. 53A illustrates image processing on image data thatincludes pixels A through I forming the step and the edge portion. FIG.53B illustrates the image processing performed on each of the pixels Athrough I.

The image processing is associated with the second detection patternthat matches the image matrix including one of the pixels A through I asa target pixel. For example, the image processing performed on the pixelA is associated with the second detection pattern that matches the imagematrix including the pixel A as a target pixel. In the presentembodiment, as illustrated in FIG. 54, the image matrix is a 9×9 matrixpattern.

Referring now to FIGS. 55A through 55C, a description is given of someexamples of the second detection pattern.

FIG. 55A is a diagram of a first example of the second detection patternto detect the pixel A as a target pixel. FIG. 55B is a second example ofthe second detection pattern to detect the pixel E as a target pixel.FIG. 55C is a diagram of a third example of the second detection patternto detect the pixel I as a target pixel.

In the present example, the pattern matching is performed by use of thesecond pattern in 9×9 matrix as illustrated in FIGS. 55A through 55C, todetect the pixel forming the step and the edge portion described above.Then, the image processing (i.e., line thinning, smoothing processing,resolution conversion) is performed. The image processing is associatedwith the second detection pattern that matches the image matrixincluding the pixel forming the step and the edge portion as a targetpixel. Accordingly, each of the pixels A through I illustrated in FIG.53A is converted as illustrated in FIG. 53B.

Referring back to FIG. 52, in the present embodiment, the selector 3268selects the second image processing pattern if the selector 3268receives both the first enable signal and the second enable signal. Ifthe selector 3268 receives the first enable signal, but does not receivethe second enable signal, the selector 3268 selects the first imageprocessing pattern. If the selector 3268 receives the second enablesignal, but does not receive the first enable signal, the selector 3268selects the second image processing pattern. If the selector 3268receives neither the first enable signal nor the second enable signal,the selector 3268 selects the normal pattern.

According to the embodiments described above, edge enhancement can beperformed without affecting image density.

Although the present disclosure makes reference to specific embodiments,it is to be noted that the present disclosure is not limited to thedetails of the embodiments described above and various modifications andenhancements are possible without departing from the scope of thepresent disclosure. It is therefore to be understood that the presentdisclosure may be practiced otherwise than as specifically describedherein. For example, elements and/or features of different embodimentsmay be combined with each other and/or substituted for each other withinthe scope of the present disclosure. The number of constituent elementsand their locations, shapes, and so forth are not limited to any of thestructure for performing the methodology illustrated in the drawings.

Each of the functions of the described embodiments may be implemented byone or more processing circuits or circuitry. Processing circuitryincludes a programmed processor, as a processor includes circuitry. Aprocessing circuit also includes devices such as an application specificintegrated circuit (ASIC), DSP (digital signal processor), FPGA (fieldprogrammable gate array) and conventional circuit components arranged toperform the recited functions.

Any one of the above-described operations may be performed in variousother ways, for example, in an order different from the one describedabove.

Further, any of the above-described devices or units can be implementedas a hardware apparatus, such as a special-purpose circuit or device, oras a hardware/software combination, such as a processor executing asoftware program.

Further, as described above, any one of the above-described and othermethods of the present disclosure may be embodied in the form of acomputer program stored in any kind of storage medium. Examples ofstorage mediums include, but are not limited to, flexible disk, harddisk, optical discs, magneto-optical discs, magnetic tapes, nonvolatilememory cards, read only memory (ROM), etc.

Alternatively, any one of the above-described and other methods of thepresent disclosure may be implemented by an application specificintegrated circuit (ASIC), prepared by interconnecting an appropriatenetwork of conventional component circuits or by a combination thereofwith one or more conventional general purpose microprocessors and/orsignal processors programmed accordingly.

What is claimed is:
 1. An image processing device comprising circuitryto: acquire an image matrix corresponding to an area, including a targetpixel and pixels surrounding the target pixel, from first image datahaving a first resolution, the first image data including a plurality ofpixels, each of the plurality of pixels including a first pixel valueindicating image information and a second pixel value indicating whetheror not each of the plurality of pixels is an area in which an object isdrawn; determine whether one or more detection patterns match the imagematrix acquired, the one or more detection patterns each including aplurality of pixels, the plurality of pixels each including the firstpixel value and the second pixel value, the one or more detectionpatterns including first patterns to detect a pixel forming an edgeportion in which each of the first pixel value and the second pixelvalue varies between pixels and including second patterns to detect apixel forming a step and the edge portion; and perform edge enhancementon the target pixel and perform resolution conversion on the targetpixel to convert the first resolution into a second resolution,relatively higher than the first resolution, to convert the target pixelinto second image data, in response to a match between the image matrixand one or more of the one or more first detection patterns or seconddetection patterns being determined, wherein in response to a matchbetween the image matrix and one or more of the one or more firstdetection patterns being determined, line thinning is performed on thetarget pixel as the edge enhancement, and resolution conversion isperformed to convert the target pixel into the second image data; and inresponse to a match between the image matrix and one or more of the oneor more second detection patterns being determined, line thinning andsmoothing processing are performed on the target pixel as the edgeenhancement, and resolution conversion is performed to convert thetarget pixel into the second image data.
 2. The image processing deviceof claim 1, wherein each of the first pixel value and the second pixelvalue is represented by 1 bit.
 3. The image processing device of claim1, wherein the object is any one of text, a line, and a graphical shape.4. The image processing device of claim 1, wherein, the circuitry isconfigured to perform image processing associated with the one or moredetection patterns determined to match the image matrix, with referenceto image processing information in which image processing correspondingto the line thinning and the resolution conversion is associated witheach of the one or more detection patterns.
 5. The image processingdevice of claim 1, wherein the circuitry further is configured toperform the resolution conversion on the target pixel to convert thetarget pixel into third image data, and select either the second imagedata or third image data.
 6. The image processing device of claim 1,wherein the circuitry further is configured to perform the resolutionconversion on the target pixel to convert the target pixel into thirdimage data, and select one of the second image data acquired by theresolution conversion performed in response to a match between the imagematrix and one or more of the one or more first detection patterns beingdetermined, the second image data acquired by the resolution conversionperformed in response to a match between the image matrix and one ormore of the one or more second detection patterns being determined, andthe third image data.
 7. A drive control device comprising: the imageprocessing device of claim 1; a generator to receive the second imagedata from the image processing device, to generate a modulation signalto control activation of a light source from the second image data; anda light source driver to drive the light source according to themodulation signal generated by the generator.
 8. The drive controldevice of claim 7, wherein an integrated device includes the imageprocessing device, the generator, and the light source driver.
 9. Alight source control device comprising: an interface unit to acquireimage data; a processor to perform image processing on the image dataacquired by the interface unit to acquire first image data; and thedrive control device of claim 7 to receive the first image data acquiredby the image processing performed by the processor.
 10. An image formingapparatus comprising: the light source control device of claim 9; thelight source driven and controlled by the light source control device;an image bearer on which a latent image is configured to be writtenaccording to light emission of the light source; a developing device tosupply toner to the latent image upon being written on the image bearerto develop the latent image into a visible toner image; a transferdevice to transfer the visible toner image, into which the latent imageis developed by the developing device, onto a recording medium; and afixing device to fix the toner image transferred by the transfer deviceonto the recording medium.
 11. An image processing device comprising:acquiring means for acquiring an image matrix corresponding to an areaincluding a target pixel and pixels surrounding the target pixel fromfirst image data having a first resolution, the first image dataincluding a plurality of pixels, each of the plurality of pixelsincluding a first pixel value indicating image information and a secondpixel value indicating whether or not each of the plurality of pixels isan area in which an object is drawn; first pattern matching means fordetermining whether one or more first detection patterns match the imagematrix, each of the one or more first detection patterns being a patternto detect a pixel forming an edge portion in which each of the firstpixel value and the second pixel value varies between pixels; and secondpattern matching means for determining whether one or more seconddetection patterns match the image matrix, each of the one or moresecond detection patterns being a pattern to detect a pixel forming astep and the edge portion; first image data converting means forperforming line thinning on the target pixel, and performing resolutionconversion to convert the first resolution into a second resolutionrelatively higher than the first resolution, to convert the target pixelinto second image data, in response to a match between the image matrixand one or more of the one or more first detection patterns beingdetermined by the first pattern matching means; and second image dataconverting means for performing line thinning and smoothing processingon the target pixel, and performing resolution conversion to convert thefirst resolution into the second resolution, to convert the target pixelinto second image data, in response to a match between the image matrixand one or more of the one or more second detection patterns beingdetermined by the second pattern matching means.
 12. The imageprocessing device of claim 11, wherein the second image data convertingmeans performs image processing associated with the one or moredetection patterns determined to match the image matrix, with referenceto image processing information in which image processing correspondingto the line thinning and the resolution conversion is associated witheach of the one or more detection patterns determined to match the imagematrix.
 13. The image processing device of claim 11, further comprising:third image data converting means for performing the resolutionconversion on the target pixel to convert the target pixel into thirdimage data; and selecting means for selecting the second image data orthe third image data.
 14. The image processing device of claim 11,further comprising: third image data converting means for performing theresolution conversion on the target pixel to convert the target pixelinto third image data; and selecting means for selecting one of thesecond image data acquired by the resolution conversion performed by thefirst converting means, the second image data acquired by the resolutionconversion performed by the second converting means, and the third imagedata.
 15. A method for processing an image, the method comprising:acquiring an image matrix corresponding to an area including a targetpixel and pixels surrounding the target pixel from first image datahaving a first resolution, the first image data including a plurality ofpixels, each of the plurality of pixels including a first pixel valueindicating image information and a second pixel value indicating whetheror not each of the plurality of pixels is an area in which an object isdrawn; determining whether one or more first detection patterns matchthe image matrix, each of the one or more first detection patterns beinga pattern to detect a pixel forming an edge portion in which each of thefirst pixel value and the second pixel value varies between pixels;determining whether one or more second detection patterns match theimage matrix, each of the one or more second detection patterns being apattern to detect a pixel forming a step and the edge portion;performing line thinning on the target pixel, and performing resolutionconversion to convert the first resolution into a second resolution,relatively higher than the first resolution, to convert the target pixelinto second image data, in response to a match between the image matrixand one or more of the one or more first detection patterns beingdetermined; and performing the line thinning and smoothing processing onthe target pixel, and performing resolution conversion to convert thefirst resolution into the second resolution, to convert the target pixelinto second image data, in response to a match between the image matrixand one or more of the one or more second detection patterns beingdetermined.
 16. The method for processing an image of claim 15, furthercomprising: performing the resolution conversion on the target pixel toconvert the target pixel into third image data; and selecting one of thesecond image data acquired by the resolution conversion performed inresponse to a match between the image matrix and one or more of the oneor more first detection patterns being determined, the second image dataacquired by the resolution conversion performed in response to a matchbetween the image matrix and one or more of the one or more seconddetection patterns being determined, and the third image data.
 17. Anon-transitory computer readable medium including program segments for,when executed by at least one processor, configuring the at least oneprocessor to perform the method of claim
 15. 18. A drive control devicecomprising: the image processing device of claim 11; a generator toreceive the second image data from the image processing device, togenerate a modulation signal to control activation of a light sourcefrom the second image data; and a light source driver to drive the lightsource according to the modulation signal generated by the generator.19. A light source control device comprising: an interface unit toacquire image data; a processor to perform image processing on the imagedata acquired by the interface unit to acquire first image data; and thedrive control device of claim 18 to receive the first image dataacquired by the image processing performed by the processor.
 20. Animage forming apparatus comprising: the light source control device ofclaim 19; the light source driven and controlled by the light sourcecontrol device; an image bearer on which a latent image is configured tobe written according to light emission of the light source; a developingdevice to supply toner to the latent image upon being written on theimage bearer to develop the latent image into a visible toner image; atransfer device to transfer the visible toner image, into which thelatent image is developed by the developing device, onto a recordingmedium; and a fixing device to fix the toner image transferred by thetransfer device onto the recording medium.